Sony WRT-847A, Руководство по обслуживанию

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3-11 WRT-847A/847B
Procedure
n
Perform the checking with the AF input connector (CN301/
MB-914 board) short-circuited.
(1) Connect the spectrum analyzer to the antenna connector
(CN402) with RF adjusting cable (and RF conversion
connector).
(2) Connect a jumper wire between the CL304 (TONE) and
CL302 (GND) on the MB-914 board (A side) by solder-
ing as shown in the above “Connections”.
(3) Set the spectrum analyzer as follow:
CENTER FREQUENCY (fc):
U14 model; 482.125 MHz
U30 model; 578.125 MHz
U62 model; 770.125 MHz
U66 model; 794.125 MHz
CE21 model; 482.000 MHz
CE33 model; 578.000 MHz
CE62 model; 810.000 MHz
CE67 model; 850.000 MHz
AU66 model; 799.250 MHz
REFERENCE LEVEL: 20 dBm
FREQUENCY SPAN: 200 kHz (20 kHz/DIV)
RBW (resolution band width): 3 kHz
VBW (video band width): 1 kHz
ATT: 20 dB
(4) Decrease gradually the DC output voltage of the DC
regulated power supply and confirm that the battery
alarm signal turns on (The BATT indicator on the LCD
will blink.) at 1
±
0.1 V.
(5) Check that level difference between carrier frequency
(center frequency level) on the spectrum analyzer and
tone signal is with in 29
±
1 dB.
2. Frequency check
Connections
(For connecting the DC power supply, refer to the “Prepara-
tions” on page 3-2.)
Procedure
n
Perform the checking with the AF input connector (CN301/
MB-914 board) short-circuited.
(1) Connect the modulation analyzer to the antenna connec-
tor (CN402) with RF adjusting cable (and RF conver-
sion connector), and connect the frequency counter to
the AF OUT connector on the modulation analyzer.
(2) Set the modulation analyzer as below;
MEASUREMENT: FM
MEASUREMENT RANGE:
±
40 kHz
HPF: 4 kHz
LPF: >20 kHz
DE EMPHASIS: OFF
(3) Set the DC output voltage of DC power supply to 1
±
0.1
V so that battery alarm signal goes on. (The BATT indi-
cator on the LCD will blink.)
(4) Check that frequency counter (resolution:0.1 Hz) read-
ing is 32.782 kHz
±
1 Hz.
(5) After the checking, remove (unsolder) the jumper wire
between CL304 (TONE) and CL302 (GND) on the MB-
914 board (A side).
Modulation
analyzer Frequency
counter
RF conversion
connector
RF adjusting
cable
CN402
MB-914 board (A side)
DP-341 board
CL302
(GND)
RF-96 board
CL304
(TONE)
Jumper
wire
Connect a jumper wire between
CL304 (TONE) and CL302 (GND) on the
MB-914 board (A side) by soldering.
(TONE signal : OFF)
fc
32.782 kHz
V : 10 dB/div
H : 20 kHz/div
29
±
1 dB
20 dBm